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Calcium mobilization is required for spreading in human osteoblasts
1University of Manchester Clinical Division I, Hope Hospital, Salford, UK.
Calcified Tissue International
|July 25, 2000
Summary
Human osteoblast adhesion to bone matrix proteins triggers a rapid, integrin-dependent increase in intracellular calcium. This calcium influx is essential for cell spreading and adhesion, highlighting its critical role in bone cell function.
Area of Science:
- Cell Biology
- Biochemistry
- Biophysics
Background:
- Osteoblast adhesion to the bone matrix is crucial for bone remodeling.
- Integrin-mediated signaling plays a key role in cell adhesion and spreading.
- Calcium ions are vital second messengers in cellular processes.
Purpose of the Study:
- To investigate the role of intracellular calcium concentration ([Ca2+]i) changes during human osteoblast adhesion.
- To determine the mechanisms and requirements of calcium mobilization during osteoblast spreading on bone matrix proteins.
Main Methods:
- Measurement of intracellular calcium concentration in human osteoblasts using fluorescent indicators.
- Adhesion and spreading assays on collagen type I, fibronectin, and laminin.
- Inhibition studies using calcium channel blockers (Carboxyamido triazole) and calcium chelators (BAPTA-AM).
Main Results:
- Osteoblast adhesion to collagen I, fibronectin, and laminin induced a rapid, approximately 2-fold increase in [Ca2+]i, followed by a decline within 1 hour.
- Calcium mobilization resulted from influx across the plasma membrane and was dependent on integrin-ligand interactions.
- Inhibitors of non-voltage-dependent calcium channels and intracellular calcium chelators dose-dependently inhibited osteoblast adhesion and spreading.
Conclusions:
- Calcium mobilization is an early event triggered by integrin-ligand contact during osteoblast adhesion.
- Calcium influx is a necessary component for successful osteoblast adhesion and spreading on bone matrix proteins.
- These findings underscore the importance of calcium signaling in osteoblast mechanotransduction and bone matrix interaction.
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